1. Field of the Invention
This invention relates to transmission of digital information over data networks. More particularly, this invention relates to operations in the routing of packets in data switching networks.
2. Description of the Related Art
The meanings of certain acronyms and abbreviations used herein are given in Table 1.
TABLE 1Acronyms and AbbreviationsASICApplication-Specific Integrated CircuitDSIDDestination Switching IdentifierHOLHead Of the LineRQReceive QueueRTTRound Trip TimeSSIDSource Switching IdentifierTQTransmit QueueVOQVirtual Output Queue
Implementation of common architectures for networks switches and routers involves modular switches. A modular data switch serves a large number of network ports and is managed as a single entity. The architecture is built of two components: 1) line card switch; and 2) fabric switch. Line card switch ports are connected to network ports and fabric switches establish connectivity between the line card switches. One connection topology in which modular switches are used is the multistage clos network. Such data switches constitute the core of common Ethernet switches, IP routers, multi-service platforms, various transmission network elements and legacy communication equipment. Buffering within the switches normally serves to resolve problems like congestion and contention among switch ports.
For example, commonly assigned U.S. Patent Application Publication No. 2011/0058571 to Gil Bloch et al., entitled Data Switch with Shared Port Buffers, which is herein incorporated by reference, describes a system of switch ports, each switch port including one or more port buffers for buffering data that traverses the switch port. A switch fabric is coupled to transfer the data between the switch ports. A switch control unit is configured to reassign at least one port buffer of a given switch port to buffer a part of the data that does not enter or exit the apparatus via the given switch port, and to cause the switch fabric to forward the part of the data to a destination switch port via the at least one reassigned port buffer.